An /etc/fstab entry for an ext4 data partition carries the single word `defaults` in its fourth field. Which set of mount options does that keyword stand for?
LPIC-1 Exam 101-500, objective 104. Devices, Linux filesystems, filesystem hierarchy standard medium
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The options
Correct rw, suid, dev, exec, auto, nouser, async
Correct. That is exactly what `defaults` expands to, and every one of those can be overridden by naming its opposite later in the same comma-separated list.
Not correct ro, nosuid, nodev, noexec, auto, nouser, sync
Wrong. This is a hardened, read-only set. It is close to what the `user` option implies for removable media, but it is not what `defaults` means.
Not correct rw, nosuid, nodev, noexec, noauto, user, async
Wrong. noauto would keep the filesystem out of `mount -a`, so the partition would not come up at boot at all.
Not correct rw, suid, dev, exec, noauto, users, sync
Wrong. sync forces every write straight to the device, which `defaults` does not do — async is the default and is what makes ordinary disk performance possible.
Why
`defaults` is shorthand, not a special mode, and the options it names are ordinary ones. Because mount applies options left to right, `defaults,ro,noexec` is the idiomatic way to start from the standard set and then tighten two of them. The keyword is also why an fstab line needs a fourth field at all when nothing unusual is wanted.
Where this comes from
- Cited
- manual page mount(8)
Practise this
Reading one question is not practice. The trainer will draw a short set from objective 104 and space the ones you get wrong.
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